List user LLM keys

{
  "keys": [
    {
      "base_url": "string",
      "created_at": "string",
      "has_key": true,
      "id": "string",
      "is_enabled": true,
      "provider": "string",
      "updated_at": "string"
    }
  ]
}

{
  "detail": "Property foo is required but is missing.",
  "errors": [
    {
      "location": "string",
      "message": "string",
      "value": null
    }
  ],
  "instance": "https://example.com/error-log/abc123",
  "status": 400,
  "title": "Bad Request",
  "type": "https://example.com/errors/example"
}